An evaluation for the design of asynchronous systems

The asynchronous circuit style is based on micropipelines, a style used to develop asynchronous microprocessors at Manchester University. This paper has presented some engineering work on developing a technique of sharing resources for micropipeline circuits. The work presented in this paper shows a comparison of 2-phase and 4-phase implementations in transistor count, speed, and energy. Though the nature of the work is mainly engineering, there are some significant new insights gained in the course of the work. In resource sharing the 2-phase implementations have better performance than the four-phase implementations. There is no "return to zero" problem. Fork and join cost nothing to the two-phase implementations. With some additional buffer stages the 4-phase implementations using the fully decoupled and long hold latch control circuits can also implement resource sharing. However, the four-phase implementations using the simple and semi-decoupled latch control circuits require more buffer stages to avoid deadlock.